I've understood that on laminar flow surfaces the "moisture" component of the airflow doesn't come into contact with the cold metal, therefore no ice can develop.
Most manufacturers fit wing de/anti-ice systems because the CAA/FAA are not entirely convinced .................but they let the tail surfaces remain unprotected to prove the point !
I've have over 10,000 hours on various 747s and although I did use the wing anti-ice systems a handful of times, it was mainly to keep the other two guys happy and not because of any evidence of wing icing. (Of course, on a Boeing747, wing anti-ice doesn't work when the leading edges are extended - which is probably the most vulnerable time to collect ice)